1. Field of the Invention
The present invention relates to a cable reel mounted on a steering apparatus of an automobile, and more particularly, it relates to an improvement in the orientation between a movable body and a fixed body of the steering apparatus to prevent a flat cable from being pinched or wedged within an annular hollow space between the movable body and the fixed body during operation of the steering apparatus.
2. Description of Background Information
FIG. 4 depicts an exemplary conventional cable real 1 mounted on the steering apparatus of a vehicle, as disclosed, for example, in Japanese Patent Application Laid-Open No. 2001-203057. A fixed body (case) 3 is attached to a steering column side of the steering apparatus, and a movable body (rotor) 2 is attached to a steering wheel (handle) side. The fixed body 3 and the movable body 2 are rotatably connected to each other. A wound flat cable 5, which electronically connects the fixed body 3 and the movable body 2, is accommodated in an annular hollow portion of the cable reel 1 between the fixed body 3 and the movable body 2. An annular elastic sheet 4 is formed on a lower surface of a rib 2b, projecting radially from a lower surface of an upper wall part 2a of the movable body 2.
As shown in FIG. 5, in the cable reel 1, a small clearance C is provided between an outer peripheral wall 3a of the fixed body 3 and a peripheral end of the elastic sheet 4 in order to prevent frictional contact between the elastic sheet 4 and the fixed body 3 during rotation of the movable body 2. The outermost winding of the flat cable 5 may therefore move into the clearance C and become sandwiched between the peripheral wall 3a of the fixed body 3 and the peripheral end of the elastic sheet 4.
When the cable reel 1 is operated (i.e., when the movable body 2 is rotated with respect to the fixed body 3) while the flat cable 5 is between the peripheral wall 3a and the peripheral end of the elastic sheet 4, the flat cable 5 may become pinched or wedged, causing damage to the flat cable 5 and/or resulting in increased or fluctuating rotational torque needed to operate the steering wheel. Furthermore, an abnormal sound may be generated by the flat cable entering the clearance C.
The present invention solves the above-described problems. Accordingly, it is an object of the present invention to provide a cable reel in which a flat cable does enter a clearance formed between an annular elastic sheet of a movable body and a peripheral wall of a fixed body. The invention therefore avoids a number of negative effects during the steering operation, including, for example, preventing abnormal sounds, damage to the flat cable, and unduly increased or fluctuating rotational torque. The present invention overcomes the problems associated with the prior art, as described below.
An aspect of the present invention provides a cable reel having a fixed body and a movable body, which is rotatably connected to the fixed body. The fixed body includes a lower wall and a peripheral member, which has a first inner periphery and a second inner periphery. The first inner periphery of the peripheral member has a smaller diameter than the second inner periphery. The movable body includes an upper wall and an annular elastic sheet connected to a bottom surface of the upper wall. The upper wall of the moveable body and the lower wall of the fixed body define an annular hollow space that houses a coiled flat cable, which is electrically connectable to the fixed body and the movable body. The upper wall of the movable body and/or the lower wall of the fixed body may include a lubricating surface. A peripheral end of the annular elastic sheet extends through the annular hollow space beyond the first inner periphery, such that the flat cable is prevented from entering a space between the peripheral end of the annular elastic sheet and the fixed body during rotation of the movable member. The peripheral end of the annular elastic sheet extends less than the second inner periphery, defining a clearance between the peripheral end of the annular elastic sheet and the second inner periphery.
The peripheral member includes a wall having a cut-out portion at an upper end, the cut-out portion defining the second inner periphery. Alternatively, the peripheral member may include multiple walls. An inner surface of an innermost wall defines the first inner periphery and an inner surface of an outermost wall defines the second inner periphery. The innermost wall is longitudinally shorter than the outermost wall, so that the annular elastic sheet extends beyond the first inner periphery above the innermost wall. At least one air space is defined between the innermost wall and the outermost wall.
Another aspect of the present invention provides a cable reel that includes a fixed body, configured to be attached to a steering column, and having a peripheral wall with an inner diameter and defining a cut-out portion at an upper end. The cable reel further includes a movable body, configured to rotate interlockingly with a steering wheel, and rotatably connected to the fixed body. A flat cable is wound in an annular hollow portion defined between the fixed body and the movable body. One end of the flat cable is connectable to the fixed body and an opposite end is connectable to the movable body, enabling electrical communication between the fixed body and the movable body. An annular elastic sheet, formed on a surface of the movable body, defines a portion of the annular hollow portion and has an outer diameter greater than the inner diameter of the peripheral wall. A peripheral end of the elastic sheet, along the outer diameter, extends into the cut-out portion of the peripheral wall of the fixed body. The flat cable is therefore contained within the inner diameter of the peripheral wall and the elastic sheet during rotation of the movable body. A clearance is provided between the peripheral end of the elastic sheet and the cut-out portion of the peripheral wall of the fixed body to enable unobstructed rotation of the elastic sheet with the movable body.
Yet another aspect of the present invention provides a cable reel that includes a fixed body, configured to be attached to a steering column, and a movable body, rotatably connected to the fixed body and configured to rotate interlockingly with a steering wheel. The fixed body has peripheral walls, such that an inner surface of an inner peripheral wall defines a first inner periphery and an inner surface of an outer peripheral wall defines a second inner periphery. The cable reel includes a flat cable, wound in an annular hollow portion defined between the fixed body and the movable body. One end of the flat cable is connectable to the fixed body and an opposite end of the flat cable being connectable to the movable body, enabling electrical communication between the fixed body and the movable body. The cable reel also includes an annular elastic sheet, formed on a surface of the movable body, defining a portion of the annular hollow portion and including a peripheral end along an outer diameter. The peripheral end of the elastic sheet extends past the first inner periphery, so that an edge portion of the flat cable, contained within the inner peripheral wall, is covered by the elastic sheet during rotation of the movable body. A clearance is provided between the peripheral end of the elastic sheet and the second inner periphery defined by the outer periphery wall, enabling unobstructed rotation of the elastic sheet with the movable body.
The inner peripheral wall has a shorter length than the outer peripheral wall. Therefore, the peripheral end of the annular elastic sheet extends past the inner periphery of the inner peripheral wall, through a space defined by the shorter length of the inner peripheral wall. At least one air space is defined between the inner peripheral wall and the outer peripheral wall.
The fixed body may further include a lower wall, such that the annular hollow portion is defined, in part, by an upper surface of the lower wall. Likewise, the movable body may further include an upper wall, such that the annular hollow portion is defined, in part, by a lower surface of the upper wall. The upper surface of the lower wall and/or the lower surface of the upper wall may include a lubricating surface.
In accordance with the various aspects of the invention, even when the flat cable in the annular hollow portion is located such that an outermost portion of the flat cable contacts the inner surface of the peripheral wall of the fixed body, the peripheral end of the elastic sheet is still positioned outward from the inner surface of the peripheral wall. Thus, an upper end of the flat cable securely contacts the lower surface of the elastic sheet, reliably preventing the flat cable from entering the space between the peripheral end of the elastic sheet and the peripheral wall. It is therefore possible to prevent an abnormal sound from being generated when the cable reel is operated (i.e., when the movable body is rotated), the flat cable from being damaged, rotational torque from increasing and fluctuation amount of the rotational torque from increasing.
The various aspects and embodiments of the present invention are described in detail below.